Lubricant-feeding material

ABSTRACT

The present invention provides a lubricant-feeding material which can be used at a temperature as high as from 100° C. to 120° C., exhibits an excellent mechanical strength and stably maintains a lubricating oil having a high polarity such as ester oil and polyphenylether oil, which have excellent lubricating properties or heat resistance, or a grease comprising such a lubricating oil as a base oil in a large amount. The lubricant-feeding material comprises a polyester elastomer comprising a hard component made of a first polyester and a soft component made of a second polyester or polyether solidified containing a lubricating oil compatible with the polyester elastomer or a grease comprising the lubricating oil as a base oil, the lubricating oil oozing from the surface of the polyester elastomer.

This is a continuation of application Ser. No. 09/240,667 filed Feb. 2,1999, abandoned, the disclosure of which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a lubricant-feeding material forfeeding a lubricant or grease to the position to be lubricated. Moreparticularly, the present invention relates to a lubricant-feedingmaterial which can be applied to parts subject to exposure to hightemperature such as rolling bearing, linear guide apparatus and ballscrew apparatus.

BACKGROUND OF THE INVENTION

In general, parts requiring good lubricating properties such as bearingare filled with a lubricating composition such as lubricating oil andsemisolid grease. However, these lubricating components, even if theyare in the form of semisolid grease, not to mention lubricating oil,become fluidized as the temperature rises during the rotation of thebearing. In order to inhibit the scattering of these lubricatingcomponents, the filled part of the bearing must be sealed by a sealingmember such as sealing plate, complicating the structure thereof. Thissealing member may not be mounted on some parts such as small-sizedbearing.

As a lubricating system requiring no sealing members there has beendeveloped a solidified lubricant-feeding material composed of a mixtureof a lubricating oil and a resin. This lubricant-feeding material hasbeen put into practical use. This resin-based lubricant-feeding materialallows a lubricating oil held in the resin to ooze to the surfacethereof to exert a lubricating action. A polyethylene having alubricating oil incorporated therein is disclosed in U.S. Pat. Nos.3,729,415, 3,547,819 and 3,541,011. JP-B-63-23239 (The term “JP-B” asused herein means an “examined Japanese patent publication”) discloses alubricant-feeding composition comprising a lubricant grease held in anultrahigh molecular polyethylene having a molecular weight of from about1×10⁶ to 5×10⁶.

These lubricant-feeding compositions are worked into a material fillingthe bearing space formed by the inner race, outer race, rolling elementsand cage of a rolling bearing as a lubricant-feeding material dependingon the lubricating position.

However, the foregoing lubricant-feeding composition made of apolyethylene and a lubricating oil or grease comprises a polyethylene asa base and is thus disadvantageous in that it begins to soften at about80° C. and then melts completely at a temperature of from 130° C. to140° C. Therefore, when the temperature is as high as not lower than 80°C., the lubricant-feeding composition shows a drop of mechanicalstrength. Namely, if the lubricant-feeding composition is mounted in thebearing as a cage or fills the bearing space, there is a fear that itcauses deformation or destruction while the rolling elements rotate atthis high temperature.

Further, the polyethylene, which is a polyolefinic synthetic resin, hasno functional groups having a high polarity, bonds (e.g., amide bond) orno aromatic rings present in its molecule and thus exhibits a poorcompatibility with a lubricating oil having a high polarity such asester oil and polyphenyl ether oil, which have excellent lubricatingproperties or heat resistance, or a grease comprising such a lubricatingoil as a base oil. Therefore, if the polyethylene comprises such alubricant incorporated therein singly or in combination with an oilhaving a low polarity being in an amount of not less than 50% by weightbased on the total amount of the lubricants, it is difficult to form alubricant-feeding material having a lubricant content of not less than50% by weight based on the total weight of the lubricant-feedingcomposition. The resulting lubricant-feeding material, if successfullyformed, allows the lubricant to ooze therefrom too early to maintain thedesired capability of feeding a lubricant because the polyethyleneexhibits an insufficient capability of holding a lubricant having a highpolarity.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide alubricant-feeding material which can be used at a temperature as high asfrom 100° C. to 120° C., exhibits an excellent mechanical strength andstably maintains a lubricating oil having a high polarity such as esteroil and polyphenylether oil, which have excellent lubricating propertiesor heat resistance, or a grease comprising such a lubricating oil as abase oil in a large amount.

The foregoing object of the present invention will become more apparentfrom the following detailed description and examples.

The foregoing object of the present invention is accomplished with alubricant-feeding material comprising a polyester elastomer and at leastone of a lubricating oil compatible with the polyester elastomer and agrease comprising the lubricating oil as a base oil, wherein thepolyester elastomer comprises a first polyester as a hard component anda second polyester or polyether as a soft component and is solidifiedcontaining the at least one of the lubricating oil and grease and thelubricating oil oozes from the surface of the polyester elastomer.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example and to make the description more clear, reference ismade to the accompanying drawings in which:

FIG. 1 is a sectional view of an essential part of an embodiment of thelubricant-feeding material according to the present invention which isapplied to a rolling bearing;

FIGS. 2(a) and 2(b) each is a sectional view of an essential part ofanother embodiment of the lubricant-feeding material according to thepresent invention which is applied to a rolling bearing (FIG. 2(a) isradially sectional view, and FIG. 2(b) is a side view);

FIG. 3 is a perspective view of an embodiment of the lubricant-feedingmaterial according to the present invention which is applied to a linearguide apparatus;

FIG. 4 is a diagram illustrating the structure of a slider containing alubricant-feeding member in the linear guide apparatus shown in FIG. 3;

FIG. 5 is a perspective view of the lubricant-feeding member shown inFIG. 4;

FIG. 6 is a sectional view of an essential part of an embodiment of thelubricant-feeding material according to the present invention which isapplied to a ball screw apparatus;

FIG. 7 is a sectional view of an essential part of an embodiment of thelubricant-feeding material according to the present invention which isapplied to a self-aligning rolling bearing; and

FIGS. 8(a) and 8(b) each is a diagram of a further embodiment of thelubricant-feeding material according to the present invention which isapplied to a rolling bearing (FIG. 8(a) is a sectional view of anessential part of the entire lubricant-feeding material, and FIG. 8(b)is a perspective view of a cage).

DETAILED DESCRIPTION OF THE INVENTION

The lubricant-feeding material according to the present invention willbe further described hereinafter.

Firstly, the polyester elastomer employable herein will be described.The polyester elastomer is a copolymer of a hard component made of afirst polyester and a soft component made of a second polyester orpolyether.

The hard component is responsible for mechanical properties,particularly hardness or heat resistance, of the entire polyesterelastomer. The soft component acts to hold a lubricant in the structureof the polyester elastomer. Accordingly, the lubricant-feeding materialaccording to the present invention exhibits excellent heat resistanceand mechanical properties as well as an excellent capability of holdinga lubricant. The polyester elastomer has a greater flexibility thanpolyethylene and thus is suitable particularly for parts which must bedeformed such as bearing seal.

The first polyester constituting the hard component is a crystallinepolyester. Specific examples of such a polyester include aromaticpolyesters such as polyethylene terephthalate, polybutyleneterephthalate and polymer of polytetramethylene glycol and 2,6-naphthalenedicarboxylic acid. The first polyester preferably has amolecular weight of 4,000 to 48,000.

These first polyesters may be used singly or in admixture.

On the other hand, the second polyester as soft component is analiphatic polyester, which preferably has a molecular weight of 4,000 to48,000. Preferred examples thereof include those represented by thefollowing chemical formula (I):

wherein a represents from 8 to 18 and m represents from 4 to 53.

The polyether as soft component is an aromatic polyether, whichpreferably has a molecular weight of 4,000 to 48,000. Preferred examplesthereof include those represented by the following chemical formula(II):

wherein b represents from 10 to 30 and n represents from 2 to 60.

The foregoing hard and soft components may be arbitrarily combined. Inpractice, however, a polyester elastomer comprising a polybutyleneterephthalate as a hard component is particularly preferred taking intoaccount the main purpose of the present invention (e.g., a fillersubstitute for grease for rolling bearing, a member which also serves asa seal provided between side seal for linear guide and slider main body,a member mounted on the end face of a ball screw, and a filler forfilling the space between the roller of self-aligning rolling bearingand the inner race, outer race and guide race).

In the foregoing use, the hardness of the polyester elastomer ispreferably from 40 to 60 (Shore D hardness), particularly from 45 to 55(Shore D hardness). The lower the hardness of the polyester elastomeris, the more lubricant can be contained therein. However, the polyesterelastomer softens when it comprises a lubricant incorporated therein.Taking into account its mechanical strength, the lower limit of thehardness of the polyester elastomer is 40 (Shore D hardness). On thecontrary, if the hardness of the polyester elastomer exceeds 60 (Shore Dhardness), the content of the soft component containing a lubricant isreduced so much. Thus, it is difficult to contain a lubricant in anamount as large as more than 50% by weight. The Shore D hardness can bemeasured according to ASTM D2240.

Accordingly, the ratio of hard component to soft component is adjustedsuch that the hardness of the polyester elastomer falls within the abovedefined range. Further, this hardness can be adjusted by selecting thelength a and b of the repeating units in the foregoing chemical formulae(I) and (II), respectively.

By incorporating a lubricating oil or grease in the foregoing polyesterelastomer, the lubricant-feeding material of the present invention canbe obtained.

The lubricating oil employable herein needs to be compatible when heatedto a temperature of not lower than the melting point of the polyesterelastomer. The lubricating oil can be incorporated in the foregoingpolyester elastomer so far as its content is extremely small regardlessof its kind. The term “compatible” as used herein is meant to indicate asystem having a lubricating oil content as very great as about 1:1 ascalculated in terms of weight ratio to polyester elastomer whichexhibits complete compatibilization at a temperature of not lower thanthe melting point of the polyester elastomer and shows uniformintegration without separation into two layers after cooling andsolidification. Specific examples of the lubricating oil compatible withthe polyester elastomer include polyphenylether oils such astetraphenylether represented by the following chemical formula:

and pentaphenylether, ester oils such as dioctyl sebacate, dioctylphthalate, trioctyl trimellitate., triisodecyl trimellitate, tetraoctylpyromellitate, pentaerythritol tetraester and dipentaerythritolhexaester, and polyalkylene glycol oils. Preferred among theselubricating oils are those having phenyl group in their structurebecause they have a higher compatibility.

The foregoing lubricating oils have a high polarity and thus may not beincorporated in some polyester elastomers in the amount described later.Accordingly, the foregoing lubricating oils may be used in admixturewith a lubricating oil having a small polarity such as mineral oil,dialkyldiphenylether oil and poly-α-olefin oil. In this case, theblended amount of such a lubricating oil having a small polarity is notmore than 30% by weight based on the total weight of the lubricatingoil. If the blended amount of such a lubricating oil exceeds the abovedefined range, the mixture disadvantageously exhibits a deterioratedcompatibility with the polyester elastomer.

The grease, if used, is produced by blending the foregoing lubricatingoil as a base oil with a lithium soap, urea compound or the like as athickener. The grease is preferably used because it stays semisolidbefore solidification and thus can easily fill the space in bearing,etc.

However, if the polyester elastomer is in the form of pellet, the greasemay hardly be mixed uniformly with the polyester elastomer even whenheated to a temperature of not lower than the melting point of thepolyester elastomer. Therefore, this pelletized polyester elastomer ispreferably pulverized into powder before use, for example, byfreeze-crushing. On the contrary, the lubricating oil to be used hereindoes not need to be in the form of powder.

Referring to the ratio of the lubricating oil or grease (hereinafterreferred to as “lubricant”) to the polyester elastomer, the content ofthe lubricant is preferably from 20 to 80% by weight, particularly from40 to 70% by weight based on the weight of the lubricant-feedingmaterial.

If the content of the lubricant falls below 20% by weight, the suppliedamount of the lubricant is reduced, eliminating the capacity of feedinglubricant too early. On the contrary, if the content of the lubricantexceeds 80% by weight, the content of the constituent polyesterelastomer is too small to obtain the predetermined mechanical strength.

The lubricant-feeding material of the present invention may comprisevarious deterioration-inhibiting additives such as antioxidant,ultraviolet absorber and hydrolyzation inhibitor, various reinforcingmaterials such as glass fiber, potassium titanate whisker and aluminumborate whisker or various solid lubricants such as PTFE and MOS₂incorporated therein.

The lubricant-feeding material of the present invention may be producedas follows.

A pelletized or powdered polyester elastomer and a lubricant are mixedat a temperature of not lower than the melting point of the polyesterelastomer to attain uniform compatibilization. The molten mixture isthen poured into a mold having the desired shape where it is then cooledand solidified.

The lubricant-feeding material of the present invention may be producedalso by injection molding. In this case, an ordinary injection moldingmachine equipped with a prefilling hopper can hardly weigh and mold thepowder obtained by grinding a solidified matter or paste prepared fromthe solidified matter as it is. The use of an improved injection machinehaving a pumping hopper as described in JP-A-8-309793 allows the powderor paste to be fairly caught by the screw, enabling weighing andmolding.

In the case of production by injection molding, an ordinary injectionmolding grade raw material, if used as a polyester elastomer, exhibitstoo low a melt viscosity when mixed with a lubricant, making it morelikely to cause the generation of fin and fail to obtain a satisfactorymolded. In order to appropriately adjust the melt viscosity of the rawmaterial, an extrusion molding grade material having a high originalmelt viscosity (preferably melt index of not more than 3.0 at atemperature of from 220 to 230° C.) may be used. When mixed with alubricant, such an extrusion molding grade material exhibits anappropriately reduced melt viscosity that allows stabilized injectionmolding.

If the lubricant-feeding material is used to fill the space in a bearingas a substitute for grease, it is preferred that a molten mixture of apolyester elastomer and a lubricant be directly injected into the spacewhere it is then solidified.

Specific examples of application of the lubricant-feeding material ofthe present invention include filler as substitute for grease forrolling bearing, member which also serves as not only a side seal butalso a seal provided in slider main body of linear guide, member mountedon the end face of a ball screw, and member provided in the space amongthe roller, inner race, outer race, and guide race of self-aligningrolling bearing. Preferred embodiments of implication of the presentinvention will be given below.

First Embodiment

Rolling Bearing

As shown in a radially sectional view of FIG. 1, a rolling bearingcomprises a plurality of rolling elements 4 rollably retained between aninner race 1 and an outer race 2 with a cage 3 provided interposedtherebetween.

In the present invention, injected into the space formed by the innerrace 1, the outer race 2, the cage 3 and the rolling elements 4, whichhas heretofore been filled by a grease or the like, is a molten mixtureof the foregoing polyester elastomer and lubricant which is thensolidified to form a lubricant-feeding material 5. The method forfilling the space with the molten mixture is not specifically limited.For example, using a grease injector with a heating mechanism, theforegoing molten mixture may be injected into the space where it is thenallowed to stand and solidify to form a lubricant-feeding material 5.Alternatively, the space in the bearing may be filled with an unmoltenmixture which is then heated and allowed to stand. Alternatively,so-called insert molding may be conducted. In other words, thelubricant-feeding material may be molded with a bearing inserted in themold.

Referring to how the rolling bearing is filled with thelubricant-feeding material 5, the lubricant-feeding material 5 may alsofill the space (indentation) between the rolling elements 4 and 4 in thecage 3 as shown in FIG. 2(a) and (b) besides in FIG. 1. The rollingbearing of the present example is provided with a sealing member 6. Inorder to fill the rolling bearing with the lubricant-feeding material 5,a molten mixture of the polyester elastomer and lubricant is injectedinto the foregoing indentation through a grease injector equipped with aheating mechanism with one side face of the rolling bearing facingupward, and then allowed to stand and solidify. Subsequently, the moltenmixture is similarly injected and solidified on the other side face.After the termination of solidification, the sealing members 6, 6 aremounted on the both ends of the outer race.

FIG. 2(a) is a radially sectional view. FIG. 2(b) is a side view of therolling bearing of FIG. 1 with the sealing member 6 being removed. Thereference numeral 7 indicates a rivet which annularly connects a pair ofcages 3.

In the various rolling bearings arranged as mentioned above, thelubricant contained in the lubricant-feeding material 5 gradually oozestherefrom to lubricate the inner race 1, the outer race 2, the cage 3and the rolling elements 4.

Second Embodiment

Linear Guide Apparatus

The present invention provides a linear guide apparatus comprising aguide rail, a slider, rolling elements, and a seal element which sealsthe opening of gap between the guide rail and slider and is disposed atboth end sides of the slider, wherein the lubricant-feeding material ofthe present invention is disposed adjacently or near to a lip portion,which is in contact with the guide rail, of the seal element.

As shown in FIG. 3, a linear guide comprises a guide rail 10 extendingaxially with rolling element rolling grooves 13A, 13B provided on theouter surface thereof and a slider mounted straddling the guide rail 10.

The slider 20 comprises a main body 20A and an end cap 20B attached toboth ends thereof. The slider main body 20A comprises a load rollingelement rolling groove (not shown) on the inner side at both wingsthereof opposed to the rolling element rolling grooves 13A, 13B on theguide rail 10 and rolling elements return path axially passing throughthe thick part of the wing. The end cap 20B comprises a curved path (notshown) connecting the rolling element rolling groove to the rollingelement return path provided parallel thereto on the slider main body20A. The rolling element rolling groove, the rolling element return pathand the curved path provided on both ends of the slider main body form arolling element circulating path. The rolling element circulating pathis loaded with many rolling elements made of, e.g., steel ball. Shown atthe reference numeral 27 is a grease nipple.

The end cap 20B is an injection-molded product of synthetic resin havingan almost U-shaped section. As shown in FIG. 4, which is a perspectiveview illustrating the assembly of the end portion of the slider 20, boththe end caps 20B have a reinforcing sheet 21, a lubricant-feeding member22 and a side seal 23 (as a seal element) fixed on the outer sidethereof in stack in order of nearness to the end cap 20B.

The reinforcing sheet 21 is a steel plate formed in an almost U-shapecorresponding to the shape of the end cap 20B. The reinforcing sheet 21comprises through-holes 21 a, 21 b for mounting screw 26 formed on bothwings thereof. Formed in the connecting portion connecting both wings isa though-hole 21 c for grease nipple. The reinforcing sheet 21 is not incontact with the guide rail 10.

The side seal 23 is formed by a steel plate formed in an almost U-shapecorresponding to the shape of the end cap 20B and a nitrile rubberhaving a shape similar to that of the steel plate formed integrally onthe outer surface of the steel plate. The inner surface of the lipportion L which comes in contact with the guide rail 10 of the side seal23 is shaped to come in sliding contact with the upper surface 10 a andouter surface 10 b of the guide rail 10 following the section of theguide rail 10 or the rolling element rolling grooves 13A, 13B so thatthe lip portion L can seal the gap between the slider 20 and the guiderail 10.

The side seal 23, too, comprises through-holes 23 a, 23 b for mountingscrew and a through-hole 23 c for grease nipple formed therein.

As shown in FIG. 5, the lubricant-feeding member 22 provided interposedbetween the reinforcing sheet 21 and the side seal 23 is formed in analmost U-shape corresponding to the shape of the end cap 20B. The innersurface of the U-shape follows the upper surface 10 a and side surface10 bof the guide rail 10. Formed on the inner surface of the U-shape areprotrusions 22 a, 22 b corresponding to the upper rolling elementrolling groove 13B on the guide rail 10 and protrusions 22 c, 22 dcorresponding to the lower rolling element rolling groove 13A on theguide rail 10 which are shaped following the crosssectional contour. Thelubricant-feeding member 22 comprises through-holes 22 e, 22 f formounting screw and a through-hole 22 g for grease nipple formed therein.

In the present invention, the lubricant-feeding member 22 is alubricant-feeding material made of polyester elastomer and lubricant.The lubricant retained in the lubricant-feeding member 22 is suppliedonto the surface thereof which comes in contact with the guide rail 10.

Shown at the reference numerals 25 a to 25 c in FIGS. 4 and 5 are ringsleeve members.

Third Embodiment

Ball Screw Apparatus

The present invention provides a ball screw apparatus comprising a screwshaft, a nut, and balls, wherein the lubricant-feeding material of thepresent invention is disposed in the nut such that the lubricant-feedingmaterial is in contact with the screw outside surface (31 c in FIG. 6)of the screw shaft.

As shown in FIG. 6, a ball screw apparatus comprises a ball nut 30provided containing a screw shaft 31. A plurality of balls 32 arerollably disposed interposed between a thread groove 30 a formed on theinner surface of the ball nut 30 and a thread groove 31 b formed on theouter surface of the screw shaft 31 opposed to the thread groove 30 a.

A cylindrical seal cap 34 is mounted on one end (right side as viewed inthe drawing) of the ball nut 30 with a bolt 35 with a lubricant-feedingmember 33 provided interposed therebetween. Mounted on the periphery ofthe axis portion of the bolt 35 is a sleeve 36. Mounted on the end ofthe seal cap 34 is a labyrinth seal 37. The labyrinth seal 37 isprovided interposed between the screw shaft 31 and the seal 34 toprevent foreign matters such as dust from entering into the apparatus.

In the present invention, the lubricant-feeding member 33 is alubricant-feeding material made of polyester elastomer and lubricant. Afine groove 33 a is formed on the outer surface of the lubricant-feedingmember 33. The lubricant-feeding member 33 is pressed radially againstthe outer surface of the screw shaft 31 at a constant pressure by agutter spring 38 disposed in the groove 33 a. In this arrangement, evenif the inner surface of the lubricant-feeding member 33 is abraded aftera prolonged operation, the lubricant-feeding member 33 can be kept inappropriate contact with the screw shaft 31, keeping the ball screwapparatus fairly lubricated.

Fourth Embodiment

Self-aligning Rolling Bearing

A self-aligning rolling bearing comprises an inner race 41 and an outerrace 42 as shown in FIG. 7. The inner race 41 comprises two lines ofrails 41 a. Provided at the ends of the rails 41 a is a rib forprevention of falling 41 b. The outer race 42 comprises rails 42 aprovided opposed to the rails 41 a on the inner race 41. Two lines ofrollers 43 are provided between the rails 41 a on the inner race 41 andthe rails 42 a on the outer race 42. The rollers 43 in each line areretained by a cage 46 integrally formed therewith. In other words, onecage 46 retains the roller 43 in each line. The cage 46 is made of hightensile brass, plastic (e.g., nylon 66) reinforced with glass fiber orthe like. Taking into account the reliability such as strength, the cage46 is preferably made of high tensile brass. Alternatively, the cage 46may be formed by integrally electron beam-welding an iron separate cageto a bearing which has previously been assembled. Guide races 47 aredisposed between the cage 46 and the inner race 41 in such anarrangement that the rollers 43 in each line can be guided.

A molten mixture of polyester elastomer and lubricant is injected intothe space between the inner race 41 and the outer race 42, the gapbetween the ribs for prevention of falling 41 b of the inner race 41 andthe outer end of the rollers 43 in each line and the gap between theinner surface of the rollers 43 in each line and the guide races 47, andthen solidified to give a lubricant-feeding material 48.

In the self-aligning rolling bearing thus assembled, the lubricantretained in the lubricant-feeding material 48 gradually oozes from thelubricant-feeding material 48 onto the inner race 41, the outer race 42,the cage 43 and the rollers 43 to keep the various rails 41 a, 42 a andthe rims 41 b lubricated over an extended period of time.

Fifth Embodiment

Rolling Bearing

In a rolling bearing, the cage can be formed by a lubricant-feedingmaterial of the present invention. For example, in the rolling bearingdescribed in JP-A-8-21450, a crown-shaped cage can be formed by thelubricant-feeding material of the present invention.

In other words, as shown in a sectional view of FIG. 8(a), a ballbearing comprises a plurality of balls 53, 53 as rolling elementsrollably retained between an inner race 51 and an outer race 52 with acrown-shaped cage 54 provided interposed therebetween. The ball bearingis provided with a sealing plate 55. The crown-shaped-cage 54 comprisesan annular main portion 56 and a plurality of sets of retaining portions57, 57 provided on one side of the main portion 56 as shown in FIG.8(b). The retaining portions 57, 57 each comprise a pair of elasticpieces 58, 58 which are arranged apart from each other.

In the present invention, the crown-shaped cage 54 acts as the foregoinglubricant-feeding material made of polyester elastomer and lubricant.Accordingly, in the ball bearing, the lubricant gradually oozes from thecrown-shaped cage 54 onto the inner race 51, the outer race 52 and theballs 53 to keep these members lubricated over an extended period oftime.

EXAMPLES

The present invention will be further described in the followingexamples, but the present invention should not be construed as beinglimited thereto.

Compatibility and Solidification Test

As shown in Table 1, to 10 g of a polyester elastomer (Pelprene P-70B,produced by TOYOBO CO., LTD.; hardness: 46 (Shore D hardness); hardcomponent: polybutylene terephthalate; soft component: polyetherrepresented by the foregoing chemical formula (II)) was added 10 g ofeach of the various lubricants. The mixture was then heated withstirring to a temperature of from 210 to 230° C., which is not lowerthan the crystalline melting point of the elastomer (200° C.), and thenallowed to cool to room temperature so that it was solidified.

During this procedure, the mixture was visually observed forcompatibility and solidification. The results are set forth in Table 1below.

TABLE 1 Results of Compatibility and Cooling/Solidification Tests Typeand Maker Compatibilization Lubricant of Lubricant during HeatingSolidification Poly-α-olefin oil SHF82, Mobile Sekiyu little Solidifiedleft K.K. compatibilization separated Mineral oil FBK Oil 150, NipponOil little Solidified left Company, LTD. compatibilization separatedDialkyl diphenyl Molesco High Loop partial Solidified left Ether LB100,Matsumura Oil compatibilization separated Research Corporation Dioctylphthalate DOP, Daihachi Chemical uniform Uniformly solidified IndustryCo., Ltd. compatibilization Trioctyl TOTM, Daihachi Chemical uniformUniformly solidified Trimellitate Industry Co., Ltd. compatibilizationPentaphenyl ether S-3105, Matsumura Oil uniform Uniformly solidifiedResearch Corporation compatibilization

A combination of triioctyl trimellitate, which shows a goodcompatibility and solidification, as a lubricant with the foregoingpolyester elastomer was used to prepare a lubricant-feeding material.

In some detail, 30% by weight of the foregoing polyester elastomer(taking into account the extrusion grade, “Hytrel 4777” (produced by DuPont-Toray Co., Ltd.; hardness: 47 (Shore D hardness); melt index: 1.5(220° C.)) was used) and 70% by weight of trioctyl trimellitate (“TOTM”,produced by Daihachi Chemical Industry Co., Ltd.) were heated to atemperature of 230° C. with stirring to make complete compatibilization.Thereafter, the molten mixture was cooled and solidified, and thenground by a grinder. The material thus ground was then molded by aninjection molding machine with a pumping hopper.

The molded product thus obtained (lubricant-feeding material) allowedthe lubricant to ooze from the surface thereof.

As mentioned above, the lubricant-feeding material according to thepresent invention can be used at temperatures as high as from 100 to120° C., where the conventional lubricant-feeding materials comprising apolyethylene as a base cannot be used, because the polyester elastomeras a base exhibits a high heat resistance. Further, thelubricant-feeding material according to the present invention cancontain a lubricant or grease having a great polarity, e.g., ester oil,which has heretofore been difficultly contained therein.

Moreover, the polyester elastomer exhibits a greater flexibility thanpolyethylene and thus is particularly suitable for use in applicationsrequiring deformation such as bearing seal.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A lubricant-feeding material comprising apolyester elastomer and either one of a lubricating oil compatible withthe polyester elastomer and a grease comprising the lubricating oil as abase oil, wherein the polyester elastomer comprises a first polyester asa hard component and a second polyester or polyether as a soft componentand is solidified containing either one of the lubricating oil andgrease and the lubricating oil oozes from the surface of the polyesterelastomer, said lubricant-feeding material comprises either one of thelubricating oil and grease in an amount of 20 to 80% by weight, saidpolyester elastomer has a hardness (Shore D) of 40 to
 60. 2. Thelubricant-feeding material of claim 1, wherein the hard component is acrystalline polyester and the soft component is at least one selectedfrom the group consisting of an aliphatic polyester and an aromaticpolyether.
 3. The lubricant-feeding material of claim 2, wherein thehard component is at least one crystalline polyester selected from thegroup consisting of polyethylene terephthalate, polybutyleneterephthalate and a polymer of polytetramethylene glycol and 2,6-naphthalenedicarboxylic acid.
 4. The lubricant-feeding material ofclaim 1, wherein the soft component is at least one selected from thegroup consisting of an aliphatic polyester represented by formula (I)and an aromatic polyether represented by formula (II):

wherein a represents from 8 to 18 and m represents from 4 to 53; and

wherein b represents from 10 to 30 and n represents from 2 to
 60. 5. Thelubricant-feeding material of claim 1, which comprises either one of thelubricating oil and grease comprising the lubricating oil as a base oilin an amount of 40 to 70% by weight.
 6. The lubricant-feeding materialof claim 1, wherein the polyester elastomer has a hardness (Shore D) of45 to 55.